There are many different versions of pressure sensors available for industrial plants and scientific laboratories at the present time. With few exceptions, these pressure sensors require one or other forms of corrective measures in order to compensate errors originating from the changing ambient conditions such as change of temperature or change of the electromagnetic properties of the ambient medium. As a matter of fact, all instruments relying on analog signals in executing the function of measurement suffer from drift of the signal resulting in error in the outcome of the measurement unless these instruments include a device that compensates for the effect of drift of the signal. An instrument operating on a digital signal generated by a physical phenomenon directly associated with the physical viriable under measurement is much preferred over the instruments operating on analog signals, because such a digitally operating instrument leaves no room for doubt as the digital instrument works accurately if it functions or it does not function at all. The present invention teaches a pressure sensor operating on a digital signal, of which frequency varies as a function of the magnitude of the pressure under measurement.